Comparing with a liquid crystal display (LCD), an organic light emitting diode (OLED), has advantages such as fast response, wide-angle view, high brightness, bright color, thinness, and is considered to be a next generation display technology.
For OLED or a polymer light emitting diode (PLED), there are two methods for forming an organic thin film layer.
First Method: Vacuum Evaporation
The first method is suitable for forming an organic thin film layer by using organic small molecular material. The first method has characteristic such as no solvent required to form the organic thin film layer and the formed organic thin film layer having a uniform thickness. However, the vacuum evaporation has disadvantages of high equipment investment and low material utilization, and is not suitable for production of a large-size product.
Second Method: Solution Process.
The second method specifically includes an inkjet printing process, a spin-coating process, a nozzle-coating process, etc. The second method is suitable for forming an organic thin film layer by using polymeric material and soluble small molecules. The second method has advantages of low equipment investment and has outstanding advantages in large-scale production of large-size products.
A continuous printing technique, which is one of the most important techniques in the solution process, has advantages of simple device and fast printing speed. In a printing process, a nozzle moves back and forth at a fast speed. As shown in FIG. 1, one problem of the continuous printing technique is that a printed organic functional thin film 3 may appear in a non-display region.
Currently, the organic functional thin film in the non-display region is removed by means of plasma etching, laser etching, solvent cleaning, etc., but by adopting the aforementioned cleaning methods, particles are introduced, which affects display effect.